Lui, the head of Macau casino operator Galaxy Entertainment, saw his fortune rise US$3.5 billion this month to US$29.6 billion, about US$100 million ahead of Li, whose fortune stood at US$29.5 billion on the Bloomberg Billionaires Index on Thursday.

Lui's family fled war-torn China for Hong Kong in 1934 where he reportedly made money selling food on the streets of the former British colony at the age of 13.

He made his first fortune after World War II when he imported construction equipment, left by U.S. forces in Okinawa, to the city.

The 84-year-old entered the Macau gambling market with Galaxy after it opened up in 2002, after a four-decade monopoly held by Hong Kong gambling mogul Stanley Ho ended.

Galaxy, which saw its shares rise more than 100 percent in 2013, is one of six firms licensed to operate casinos in Macau, the world's biggest gaming hub, which was handed back to Beijing in 1999 and remains the only Chinese city where casino gambling is allowed.

Macau's gambling revenue jumped 18.6 percent to a record US$45 billion in 2013, official figures showed earlier in the month.

Li Ka-shing started out in business as a plastic flower-maker but now commands a vast empire through Cheung Kong Holdings and Hutchison Whampoa, with global assets in property, telecoms, utilities, ports and retail.

The 85-year-old was Asia's richest man starting April 2012 after he surpassed Indian billionaire Mukesh Ambani, according to the index.

The Bloomberg Billionaires Index lists American Jim Walton, founder of retailer Wal-Mart, as the richest in the world, with a fortune of US$36.5 billion.

He was followed by Amazon's Jeff Bezos with a net worth of US$35.7 billion.

The index, which ranks Lui and Li at 21 and 22, is a daily ranking of the world's richest people.